Coil and solenoid incorporating same

ABSTRACT

The coil bobbin has a terminal support integral with one end flange. The terminals are inserted into the terminal slots in the support after the wire is wound on the bobbin. The slots are tapered so the terminal end which passes through the slot must be forced and a seal around the terminal results. The seal prevents leakage past the terminal when the coil is encapsulated. The bobbin interior forms a core guide and the bobbin includes projecting integral guides for the solenoid core, thus eliminating the usual metal guides. One side flange of each guide is cut back to receive a tang of a metal bracket. The tang serves to hold the core in place and projects into the groove on the side of the core to function as a core stop when the end of the groove hits the tang.

United States Patent [191 Yatsushiro et al.

[ Dec. 23, 1975 COIL AND SOLENOID INCORPORATING SAME [73] Assignee:Controls Company of America,

Schiller Park, 111.

[22] Filed: Nov. 22, 1974 [21] Appl. No.: 526,073

3,530,572 9/1970 Conrath 335/248 X 3,566,322 2/1971 Horbach 3,593,2407/1971 Garcznski 335/249 Primary Examiner-G. Harris Attorney, Agent, orFirm-Michael, Best & Friedrich [57] ABSTRACT The coil bobbin has aterminal support integral with one end flange. The terminals areinserted into the terminal slots in the support after the wire is woundon the bobbin. The slots are tapered so the terminal end which passesthrough the slot must be forced and a seal around the terminal results.The seal prevents leakage past the terminal when the coil isencapsulated. The bobbin interior forms a core guide and the bobbinincludes projecting integral guides for the solenoid core, thuseliminating the usual metal guides. One side flange of each guide is cutback to receive a tang of a metal bracket. The tang serves to hold thecore in place and projects into the groove on the side of the core tofunction as a core stop when the end of the groove hits the tang.

6 Claims, 14 Drawing Figures US. Patent Dec. 23, 1975 Sheet 1 Of23,928,831

COIL AND SOLENOID INCORPORATING SAME BACKGROUND OF THE INVENTION Inmanufacture of solenoids of the general type shown herein the art hasadopted the encapsulated coil as a standard in high volume production.Encapsulated coils are cheaper and better. Prior coil designs, however,have used separate bridges to support the terminals and have requiredthree or more mold sections (with resultant high cost) or tape wrappedwith undesirable cost penalties. Further, the prior designs haverequired core guides inside the bobbin which used costly metal parts andincreased the wire-to-core gap with consequent reduction in magneticcoupling.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a coil design which completes the magnet wire termination withminimal labor and parts while providing firm support for the terminals.Another object is to design the coil bobbin to permit high pressureencapsulation with a 2-section mold while avoiding flash on thetenninals. These objectives are achieved by the design described abovewhich supports the terminals on a bobbin flange extension and seals andgrips the terminals to prevent flash and pull-out of the terminals.

Another object is to eliminate the customary core guides. This isaccomplished by molding the bobbin with integral guide extensions. As aconsequence the magnetic coupling is closer and the working force isincreased or for the same force less wire is required.

A final object is to provide a solenoid construction incorporating thecoil and providing a core stop which also retains the core in theassembly. This is accomplished by providing a tang which projects from abracket through a cutout in the bobbin guide flange into a goove on thecore while the bracket retains the coil.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the bobbin.

FIG. 2 is a fragmentary plan view of the terminal end of the bobbin.

FIGS. 3 and 4 are, respectively, horizontal and vertical sectionsthrough the terminal slots of the bobbin.

FIG. 5 is a perspective of the bobbin after winding and mounting theterminals.

FIG. 6 is a fragmentary horizontal section showing the manner in whichthe terminal is mounted in the slot.

FIG. 7 is a vertical section showing the terminal mounted in the slot.

FIG. 8 is a top plan view of the encapsulated coil.

FIG. 9 is a side elevation of the encapsulated coil.

FIG. 10 is an end view of the encapsulated coil.

FIG. 11 is a section through the coil taken on line llll in FIG. 10.

FIG. 12 is a plan view of the core.

FIG. 13 is a side elevation of the core.

FIG. 14 is a plan view of the assembled solenoid.

DESCRIPTION OF THE PREFERRED EMBODIMENT The bobbin 10 is spool-like inappearance with a smooth, generally rectangular central bore 12 and hasguide channels 14 projecting from one end to extend the core guidingsurface. It 'will be noted that each guide channel has side flanges l6and one corner of the flange is cut out at 18 to receive the core stoptang as will appear more fully hereinafter. The bobbin has end flanges20,22 between which the magnet wire is wound. The larger flange 20projects upwardly and flares outwardly and includes thickened portions24 through which slots are provided to receive terminals. As can be seenin FIGS. 3 and 4, these slots are tapered inwardly towards the wire sideof the flange. Thus in FIG. 3 there is a rounded entry into the slot 26and the slot tapers inwardly from the entry. As can be seen in FIG. 4,the slot in vertical section has a straight portion leading to a ratherabrupt inward taper at the wire side of the slot. Thus when the terminal28 is pressed in from the outside, the small portion 30 of the terminalmust be forced into the slot and it achieves a good mechanical fit whilesealing the terminal relative to the end flange 20. This seal preventsthe encapsulating material from being forced out along the terminal andgetting onto the spade portion of the terminal which would requirehandwork to clean up the terminal.

Magnet wire 34 is wound on the bobbin and then the terminals are pressedin from the outside, as in FIG. 5.

Then the magnet wire is mechanically connected to the slots 32 in theterminal end and preferably then soldered or welded. The coil is nowready for encapsulation and a 2-part or section mold is clamped onto theend flange of the bobbin securely enough to permit high pressureinjection or transfer molding. The encap-..

sulant covers the wire 34 completely and locks onto the flanges as maybe seen in FIG. 11. Thus the perimeter of each flange is slightlyreduced at 36 so the encapsulant can flow slightly over the end of theflange. The portion adjacent the tenninals is molded with the incline 38and the flares 40. This completely encloses the terminals on the inside.This locks the terminals in the assembly and there is no danger ofterminal pull-out.

The solenoid core is designated by reference numeral 42 and comprises astack of laminations 44 with the outside of the stack on each sidehaving a heavier piece of metal 46 running down the length and then bentin at one end to provide the connection point for the device to beactuated. It will be noted that a groove 48 is provided on each side ofthe core. This groove is to receive the core stop tang, as will appearhereafter.

The solenoid has a C-frame 50. The laminations on the closed end of theframe are formed so as to provide a projection 52 into the center of thecoil which serves to center the end of the bobbin in the frame. The coilis placed in the C-frame after shading coils 54 are positioned in place.Then the kickout springs 56 are positioned in the assembly, the core isput into the coil and the coil stop members 58 are riveted into place.It will be noted that the stops 58 are formed to provide a channel-likeportion 60 which cooperates with the extending plastic core guide toreinforce the core guide. Also each stop has a tang 62 which projectsthrough the cutout comer 18 of the guide and into the groove 48 on eachside of the core. The bracket holds the coil relative to the frameand'the tang cooperates with the inboard end 64 of the groove to limitoutward movement of the core.

It should be noted each of the two guides has side flanges which guidethe stem of the core in one direction while the flat of the guides guidein the other direction. The guides obviously could be one tubularmember. Therefore, in the claims the use of the term guides is meant toembrace a tubular guide since it has plural guide surfaces. Theadvantage of the channel-like guides (beyond using less material)resides in the fact the space between the flanges on each side canaccept and permit use of the shoulders 66 under the head 68 of the core.These shoulders increase the pull of the solenoid at the stage of travelwhere pull normally drops off (see US. Pat. No. 2,468,052). The channelguides obviously are not as strong as a tubular guide would be. But thebrackets 58 closely embrace the guides on all sides and reinforce theguides.

By way of recapitulating some of the advantages of the presentconstruction, it will be noted that the metal core guides heretoforeemployed in solenoid manufacture have been eliminated and the wire,therefore, is closer to the iron of the core. This means there is closermagnetic coupling which develops a greater working force for the samecoil winding, or for the same working force the amount of copper wirecan be reduced. There is minimal amount of labor involved in winding thecoil and assembling the terminals since there are no separate pieces tobe handled insofar as providing bridges and the like for the terminals.Furthermore, the method of mounting the terminal into the bobbin flangeinsures against any flash on the terminals which would require handcleanup. The coil is designed to be molded in a 2-part mold whichinherently results in the least cost of manufacture of the mold and alsorequires minimal maintenance. There is no need to design the mold toseal around the terminals. The terminal insertion in the flange providesa complete seal against the encapsulating material working along theterminals during the high pressure encapsulating process. Finally, inthe assembly of the solenoid the brackets hold the coil in positionwhile the core stops provide a simple and effective means forcontrolling core withdrawal.

We claim:

1. A coil comprising a coil bobbin having a spool-like central portionand a flange on each end of the central portion,

a wire wound on the central portion of the bobbin,

one of the flanges being extended and being provided with two terminalreceiving slots located beyond the depth of the wire wound on the spoolwith each 5 slot being tapered in both directions from the outside ofthe flange towards the spool side of the flange,

a terminal mounted in each slot and sized to require a sealing force-fitbetween the terminal and the extended flange,

the ends of the wire being connected to said terminals,

encapsulating material surrounding the wire and the inside ends of theterminals,

integral opposed guides projecting beyond the central portion of thebobbin with the inside surfaces of the guides being aligned with andforming a continuation of the inside surface of the bobbin, each guidehaving three guiding surfaces.

2. A solenoid having a frame, a core and the coil according to claim 1,

said core being guided in the bobbin and guides and having a groovealong one side,

and a bracket connected to the frame and including a tang projectinginto said groove to act as a limit stop when the end of the groovestrikes the tang.

3. A solenoid according to claim 2 in which the tang engages the guideto retain the core.

4. A solenoid according to claim 3 in which each guide is channel-likeand a bracket fits over each projecting guide to reinforce the guide.

5. A solenoid according to claim 4 in which the side flange of the guideis cut away to receive the tang.

6. A solenoid according to claim 5 in which the confronting side flangesof the channel-like guides are spaced far enough to permit passage of anenlarged section of the core stem.

1. A coil comprising a coil bobbin having a spool-like central portionand a flange on each end of the central portion, a wire wound on thecentral portion of the bobbin, one of the flanges being extended andbeing provided with two terminal receiving slots located beyond thedepth of the wire wound on the spool with each slot being tapered inboth directions from the outside of the flange towards the spool side ofthe flange, a terminal mounted in each slot and sized to require asealing force-fit between the terminal and the extended flange, the endsof the wire being connected to said terminals, encapsulating materialsurrounding the wire and the inside ends of the terminals, integralopposed guides projecting beyond the central portion of the bobbin withthe inside surfaces of the guides being aligned with and forming acontinuation of the inside surface of the bobbin, each guide havingthree guiding surfaces.
 2. A solenoid having a frame, a core and thecoil according to claim 1, said core being guided in the bobbin andguides and having a groove along one side, and a bracket connected tothe frame and including a tang projecting into said groove to act as alimit stop when the end of the groove strikes the tang.
 3. A solenoidaccording to claim 2 in which the tang engages the guide to retain thecore.
 4. A solenoid according to claim 3 in which each guide ischannel-like and a bracket fits over each projecting guide to reinforcethe guide.
 5. A solenoid according to claim 4 in which the side flangeof the guide is cut away to receive the tang.
 6. A solenoid according toclaim 5 in which the confronting side flanges of the channel-like guidesare spaced far enough to permit passage of an enlarged section of thecore stem.